2010 having 18 #1's and 2014 having 9 #1's is just a case of one year having above-average amount of #1's and another year having a below-average amount of #1's.
Just the year before 2009 had 12 #1's, and the year after 2011 had 13 #1's.
9 #1's is really low tho. Lowest since 2005 / 2003 had the lowest amount of #1's in a year. A lot of Streaming monsters happened last year though (Fancy, All About that Bass, Blank Space) with a mix of crossover airplay monsters (Dark Horse, Happy, All Of Me) so ofcourse the stays were really long.
only girls who have had their period for the first time in the last 365 days are allowed to like it.