Major efforts have been made to combat disinformation and trolling on Twitter, due to their impact on election results across the globe. Even so, trolling seems to be as prevalent as ever before. We aim to examine if and how the extent of trolling toward political figures on Twitter changed between the 2016 and 2020 US presidential election cycles by analyzing outrage comments made towards tweets by a total of 20 Democrat and Republican candidates for President/VP and Senate/House. Based on content analysis of 9,461 comments, we found significantly more trolling towards Republicans than Democrats, demonstrating trolling asymmetry. We also found that between 2016 and 2020, there was a significant increase in overall trolling towards Republicans, but not in overall trolling towards President/VP candidates, highlighting a more obvious increase in domestic trolling than that of the external interference in election results.