Income taxes	9 Months Ended
Sep. 30, 2016
Income taxes
Income taxes	Note 4. Income taxes For the nine months ended September 30, 2016 and 2015, our income tax expense has been computed utilizing the estimated annual effective rates of 35.8% and 40.1%, respectively. The decrease in the estimated annual effective tax rate is primarily due to the apportionment of income before income taxes for state income tax purposes in 2016 due to the expansion of our business, which resulted in a reduced state tax rate. The difference between the annual effective rate in both periods and the statutory Federal income tax rate of 35% is primarily due to state income taxes and foreign withholding taxes offset by foreign tax credits. Income tax expense for the three and nine months ended September 30, 2016 was $2.3 million and $6.6 million, respectively. Income tax expense for the three and nine months ended September 30, 2015 was $2.0 million and $5.9 million, respectively.

Income taxes

9 Months Ended

Sep. 30, 2016

Note 4. Income taxes

For the nine months ended September 30, 2016 and 2015, our income tax expense has been computed utilizing the estimated annual effective rates of 35.8% and 40.1%, respectively. The decrease in the estimated annual effective tax rate is primarily due to the apportionment of income before income taxes for state income tax purposes in 2016 due to the expansion of our business, which resulted in a reduced state tax rate. The difference between the annual effective rate in both periods and the statutory Federal income tax rate of 35% is primarily due to state income taxes and foreign withholding taxes offset by foreign tax credits.

Income tax expense for the three and nine months ended September 30, 2016 was $2.3 million and $6.6 million, respectively. Income tax expense for the three and nine months ended September 30, 2015 was $2.0 million and $5.9 million, respectively.