Q: Passage: Following the lead of minor leagues, as of the 2005 -- 06 season, the NHL ends exhibition and regular season games still tied after a five-minute-length, three-skaters-per-side overtime period (as of the 2015 -- 16 NHL season onwards) with a shootout. The NHL format is a three-round shootout with tiebreaker rounds as needed. All skaters (except goalies) on a team's roster must shoot before any player can shoot a second time. On December 16, 2014 the longest shootout in NHL history went to 20 rounds before Nick Bjugstad of the Florida Panthers scored to defeat the Washington Capitals; the previous record was 15 rounds.

Question: Based on this passage, what was the longest shootout in nhl history?
Let's give stream of consciousness below

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
To answer the above question, the relevant sentence is: On December 16, 2014 the longest shootout in NHL history went to 20 rounds before Nick Bjugstad of the Florida Panthers scored to defeat the Washington Capitals; the previous record was 15 rounds. So the answer is 20 rounds.