The 2009 Employee Stock Purchase Plan (2009 ESPP) allows for the issuance of 3.0 million shares of our common stock. The 2009 ESPP is intended to qualify as an “Employee Stock Purchase Plan” under Section 423 of the Internal Revenue Code of 1986, as amended, and is administered by the Compensation Committee of the Board of Directors. As of December 31, 2023, 1.0 million shares were available for purchase pursuant to the 2009 ESPP.

Eligible employees are entitled to defer up to 10% of their base pay for the purchase of stock, up to $25,000 of fair market value of our common stock annually. The purchase price is equal to 85% of the fair market value at the end of the purchase period. Compensation expense related to our 2009 ESPP is calculated based on the 15% discount from the per share market price on the date of grant.

For the year ended December 31, 2023, 124,154 shares were purchased pursuant to the 2009 ESPP at a weighted average price per share of $235.64, with weighted average per share discount from market value of $41.58.


	Year Ended December 31,
	2023		2022		2021
Cash received related to ESPP purchases ($ in millions)	$	29.3	$	34.4	$	29.6
Tax deductions associated with ESPP disqualifying dispositions ($ in millions)	$	3.9	$	3.1	$	1.9
Weighted average per share discount for compensation expense recognized	$	41.58	$	38.57	$	50.58

Our 2013 Stock Incentive Plan, as amended, (2013 Plan) allows for the grant of a total of 3.8 million shares in the form of stock appreciation rights, qualified stock options, non-qualified stock options, restricted share awards and restricted stock unit awards (RSUs) to our officers, key employees, directors and consultants. The 2013 Plan is administered by the Compensation Committee of the Board of Directors and permits accelerated vesting of outstanding awards upon the occurrence of certain changes in control. As of December 31, 2023, 718,731 shares of common stock were available for future grants. As of December 31, 2023, there were no stock appreciation rights, qualified stock options, non-qualified stock options or restricted share awards outstanding.


	RSUs	Weighted average per share grant date fair value
Balance, December 31, 2022	415,878	$	159.85
Granted	327,955	302.35
Vested	(182,056)	174.61
Forfeited	(32,101)	214.41
Balance, December 31, 2023	529,676	287.04

We granted 48,872 time-vesting RSUs to members of our Board of Directors and employees in 2023. Each grant entitles the holder to receive shares of our common stock upon vesting. A portion of the RSUs vest over three years for employees and vest quarterly for our Board of Directors, over their service period.

We granted 279,083 performance and time-vesting RSUs to our employees in 2023. These shares will be earned either over one or three-year performance periods based on attaining various target levels of operational performance, as well as market-based returns. These RSUs will vest over three or four years from the grant date.

Time-vesting RSUs and performance and time-vesting RSUs that are based on our financial performance metrics or non-financial operating goals are valued using the market value of our common stock on the date of grant, discounted for the present value of expected dividends. On the date of grant, we estimated the fair value of the total shareholder return (TSR) component of the performance and time-vesting RSUs using a Monte Carlo simulation model. The performance and time-vesting RSUs granted during the years presented are contingent on the achievement of our financial performance metrics, our comparative market-based returns, or the achievement of financial and non-financial operating goals.


	Year Ended December 31,
	2023			2022			2021
Time-vesting RSUs
Number of shares granted	48,872			18,080			33,665
Grant date fair value per share	$	268.60		$	283.86		$	312.83
Weighted-average assumptions/inputs:
Expected dividend yield	0.6		%	0.5		%	0.4		%
Range of risk-free interest rates	3.6% - 4.7%			1.2% - 4.5%			0.3% - 1.0%

Performance and Time-vesting RSUs
Number of shares granted	279,083			120,340			94,001
Grant date fair value per share	$	313.84		$	296.28		$	308.59
Weighted-average assumptions/inputs:
Expected dividend yield	0.6		%	0.5		%	0.4		%
Range of risk-free interest rates	3.6% - 4.5%			0.4% - 3.2%			0.3% -0.7%


	Year Ended December 31,
($ in millions)	2023		2022		2021
Number of shares vested	182,056		147,441		141,857
Weighted average per share fair value of non-vested shares that vested during the period	$	174.61	$	110.77	$	107.50
Tax deduction realized related to shares that vested during the period ($ in millions)	$	25.8	$	20.3	$	26.3

Share-based compensation is recognized as a component of SG&A in our Consolidated Statements of Operations. SG&A expense related to all share-based compensation is as follows:


	Year Ended December 31,
($ in millions)	2023		2022		2021
Restricted stock unit awards	$	35.6	$	35.0	$	29.5
Employee stock purchase plan	5.2		6.1		5.2
Total share-based compensation	40.8		41.1		34.7
Tax expense recognized	(7.6)		(6.4)		(8.1)
Net reduction in net income	$	33.2	$	34.7	$	26.6

As of December 31, 2023, unrecognized share-based compensation related to outstanding, but unvested RSUs was $56.5 million, which will be recognized over the remaining weighted average vesting period of 2.7 years.