Yahoo! reported the following in its 2016 financial statements (in thousands):
December 31, 2016 December 31, 2015 December 31, 2014
Revenues $5,169,135 $4,968,301 $4,618,133
Product development expense . $1,055,462 $1,177,923 $1,156,386
What trend do you notice in Yahoo's spending for product development?