On 11 February 2016, the LIGO and Virgo collaborations announced the first observation of gravitational waves. The signal was named GW150914.\cite{Castelvecchi_2016}The waveform showed up on 14 September 2015, within just two days of when the Advanced LIGO detectors started collecting data after their upgrade.
"In 2017, LIGO saw four further gravitational waves: the first (GW170104) in January; the second (GW170608) in June; the third (GW170814) and the fourth (GW170817) both in August. GW170814 and GW170817 were also seen by the Virgo Collaboration.Unlike the black hole mergers which are only detectable gravitationally, GW170817 came from the collison of two neutron stars and was also detected electromagnetically by gamma ray satellites and optical telescopes."\cite{release}
It is generally believed by the LSC that LIGO will keep detecting the gravational waves from the universe. The latest detection caused by the collison of two neutron stars proved its sensitivity, and the LSC is keep improving the details of interferometer.
Summary
LIGO's success wasn't a coinincidence. It is a huge achievement in human's scientific history which relys on the persistance of the brilliant minds and the continuous support from the universities and the government.
With the development of other detectors like Virgo(find the first gravtional waves with LIGO) and InDIGO(a planned LIGO in India), more and more countries have joined the cause of detecting the "ripples" of universe. Therefore, it won't be strange that we are going to expierence an "outbreak" of gravitational waves.