| Summary of quarterly financial data |
Summarized quarterly financial data for December 31, 2015 and 2014:
| | | | | | | | | | | | | | | | | | Year Ended December 31, 2015 | | Quarter | | First | | Second | | Third | | Fourth | | | | | | | | | | (in thousands, except per unit data) | Net sales | $ | 93,050 |
| | $ | 80,815 |
| | $ | 49,325 |
| | $ | 66,004 |
| Operating costs and expenses: | | | | | | | | Cost of product sold (exclusive of depreciation and amortization) – Affiliates | 1,818 |
| | 2,184 |
| | 1,147 |
| | 1,552 |
| Cost of product sold (exclusive of depreciation and amortization) – Third parties | 23,951 |
| | 13,240 |
| | 13,354 |
| | 7,943 |
| | 25,769 |
| | 15,424 |
| | 14,501 |
| | 9,495 |
| Direct operating expenses (exclusive of depreciation and amortization) – Affiliates | 1,027 |
| | 1,195 |
| | 1,030 |
| | 841 |
| Direct operating expenses (exclusive of depreciation and amortization) – Third parties | 23,387 |
| | 23,951 |
| | 32,149 |
| | 22,476 |
| | 24,414 |
| | 25,146 |
| | 33,179 |
| | 23,317 |
| Selling, general and administrative expenses (exclusive of depreciation and amortization) – Affiliates | 3,267 |
| | 3,361 |
| | 3,661 |
| | 3,672 |
| Selling, general and administrative expenses (exclusive of depreciation and amortization) – Third parties | 1,316 |
| | 1,162 |
| | 2,381 |
| | 1,948 |
| | 4,583 |
| | 4,523 |
| | 6,042 |
| | 5,620 |
| Depreciation and amortization | 6,819 |
| | 7,010 |
| | 7,409 |
| | 7,214 |
| Total operating costs and expenses | 61,585 |
| | 52,103 |
| | 61,131 |
| | 45,646 |
| Operating income (loss) | 31,465 |
| | 28,712 |
| | (11,806 | ) | | 20,358 |
| Other income (expense): | | | | | | | | Interest expense and other financing costs | (1,697 | ) | | (1,717 | ) | | (1,727 | ) | | (1,739 | ) | Interest income | 12 |
| | 12 |
| | 10 |
| | 6 |
| Other income, net | 6 |
| | 5 |
| | 54 |
| | 99 |
| Total other income (expense) | (1,679 | ) | | (1,700 | ) | | (1,663 | ) | | (1,634 | ) | Income before income tax expense (benefit) | 29,786 |
| | 27,012 |
| | (13,469 | ) | | 18,724 |
| Income tax expense (benefit) | 12 |
| | (4 | ) | | 9 |
| | (7 | ) | Net income (loss) | $ | 29,774 |
| | $ | 27,016 |
| | $ | (13,478 | ) | | $ | 18,731 |
| Net income (loss) per common unit – basic | $ | 0.41 |
| | $ | 0.37 |
| | $ | (0.18 | ) | | $ | 0.26 |
| Net income (loss) per common unit – diluted | $ | 0.41 |
| | $ | 0.37 |
| | $ | (0.18 | ) | | $ | 0.26 |
| Weighted-average common units outstanding: | | | | | | | | Basic | 73,123 |
| | 73,123 |
| | 73,123 |
| | 73,123 |
| Diluted | 73,131 |
| | 73,131 |
| | 73,123 |
| | 73,131 |
|
| | | | | | | | | | | | | | | | | | Year Ended December 31, 2014 | | Quarter | | First | | Second | | Third | | Fourth | | | | | | | | | | (in thousands, except per unit data) | Net sales | $ | 80,316 |
| | $ | 77,215 |
| | $ | 66,733 |
| | $ | 74,401 |
| Operating costs and expenses: | | | | | | | | Cost of product sold – Affiliates | 2,246 |
| | 2,327 |
| | 2,232 |
| | 2,619 |
| Cost of product sold (exclusive of depreciation and amortization) – Third parties | 19,462 |
| | 17,109 |
| | 13,202 |
| | 12,755 |
| | 21,708 |
| | 19,436 |
| | 15,434 |
| | 15,374 |
| Direct operating expenses (exclusive of depreciation and amortization) – Affiliates | 753 |
| | 817 |
| | 621 |
| | 833 |
| Direct operating expenses (exclusive of depreciation and amortization) – Third parties | 23,436 |
| | 26,100 |
| | 25,487 |
| | 20,911 |
| | 24,189 |
| | 26,917 |
| | 26,108 |
| | 21,744 |
| Selling, general and administrative expenses (exclusive of depreciation and amortization) – Affiliates | 3,536 |
| | 3,973 |
| | 3,035 |
| | 2,867 |
| Selling, general and administrative expenses (exclusive of depreciation and amortization) – Third parties | 1,118 |
| | 1,297 |
| | 928 |
| | 949 |
| | 4,654 |
| | 5,270 |
| | 3,963 |
| | 3,816 |
| Depreciation and amortization | 6,667 |
| | 6,792 |
| | 6,812 |
| | 6,978 |
| Total operating costs and expenses | 57,218 |
| | 58,415 |
| | 52,317 |
| | 47,912 |
| Operating income | 23,098 |
| | 18,800 |
| | 14,416 |
| | 26,489 |
| Other income (expense): | | | | | | | | Interest expense and other financing costs | (1,659 | ) | | (1,669 | ) | | (1,724 | ) | | (1,731 | ) | Interest income | 6 |
| | 6 |
| | 7 |
| | 11 |
| Other income, net | 15 |
| | — |
| | 33 |
| | 23 |
| Total other income (expense) | (1,638 | ) | | (1,663 | ) | | (1,684 | ) | | (1,697 | ) | Income before income tax expense (benefit) | 21,460 |
| | 17,137 |
| | 12,732 |
| | 24,792 |
| Income tax expense (benefit) | 7 |
| | 7 |
| | 13 |
| | (55 | ) | Net income | $ | 21,453 |
| | $ | 17,130 |
| | $ | 12,719 |
| | $ | 24,847 |
| Net income per common unit – basic | $ | 0.29 |
| | $ | 0.23 |
| | $ | 0.17 |
| | $ | 0.34 |
| Net income per common unit – diluted | $ | 0.29 |
| | $ | 0.23 |
| | $ | 0.17 |
| | $ | 0.34 |
| Weighted-average common units outstanding: | | | | | | | | Basic | 73,113 |
| | 73,113 |
| | 73,115 |
| | 73,117 |
| Diluted | 73,145 |
| | 73,146 |
| | 73,139 |
| | 73,133 |
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