At the 2017 All-Star break the Twins record from 1961 to current stands at 4,461 wins and 4,560 losses. The Twins have won a total of 410 games in walk-off fashion and lost 412 games via the walk-off. The means that 09.11% of the Twins games end via a walk-off in one fashion or another.
The best season the Twins have ever had for walk-off wins was 1987 when they had 16 walk-off victories. The fewest walk-off wins occurred in 1982 when they had just two. So far in 2017 they have also had just two walk-off wins.
Naturally there is the other side of the coin and the Minnesota Twins suffered 15 walk-off defeats in 1964 but only had three in 1993 and 2006. So far this season they have just one walk-off loss.