12.	INCOME TAXES

The provision for income taxes is based on a current estimate of the annual effective income tax rate adjusted to reflect the impact of discrete items. Significant management judgment is required in estimating operating income in order to determine our effective income tax rate. The estimated effective income tax rate was 41.79% and 42.13% for the three and nine months ended September 30, 2015, respectively. The estimated effective income tax rate was 38.57% and 39.11% for the three and nine months ended September 30, 2014, respectively. The higher effective income tax rate for the three and nine months ended September 30, 2015 is primarily the result of an increase in the applicable statutory federal tax rate.