The 25-year-old, who joined the club from Vitesse Arnhem last summer, has scored 19 goals in all competitions during the current campaign, but he believes that he could have contributed more to the team.
"Am I pleased with my season? Personally, I'm maybe 50-50," the Daily Star quotes the forward as saying. "I should have done more, but I'm happy with what I'm doing now.
"There are still some games left and I will try to do my best and then I will judge again. We need to bring the best parts of this game in the next game now."
Swansea are currently 15th in the Premier League, five points above the relegation zone.