The LIGO press release mentions an estimation of
black hole merger rates — «about one every 10 years in a volume a trillion times the size of the Milky Way Galaxy» — based on how many signals it's detected so far.
Not exact matches
This suggests LIGO — which is in the midst of upgrades to boost its sensitivity and planning for a new station in India — could eventually be detecting the chirps from
black hole mergers at a
rate of anywhere between once per day to once per week.