Travelers posted 27% more hotel reviews in 2017 than a year earlier, and most of that growth can be attributed to Google.

The findings are part of the Global Hotel Reputation Benchmark Report prepared by Revinate, a software and data analytics company for hotels that analyzed 132 million online guests reviews from 138,000 properties across 200 countries.

Nearly three-quarters of all reviews come from the top four sites: Booking.com, Google, TripAdvisor and Facebook.

Booking.com retained its lead as the top review aggregator, but Google is gaining ground. Reviews on the site in 2017 were more than 200% above the 2016 level, with about two-thirds of that content posting between July and December.

Google reviews accounted for 70% of the net review growth across all sites in 2017. Without the Google data, Revinate says the year-over-year growth in reviews would have been just 9% -- not 27%.