How many people commit suicide on the Hoover Dam?

I've heard different answers. I've been on the tour, and the tour guide said it happens about once a year. I've read that the official number is about 20 since construction, but someone who worked there told me it happens about every other week - more during the holidays.

my aunt commited suicide on the hoover dam in November of 1998. i have known of others that have as well... i believe it is around 112 people...and still counting