| Year | Ranking of major obstacle factors | ||||
|---|---|---|---|---|---|
| 1st obstacle factor | 2nd obstacle factor | 3rd obstacle factor | 4th obstacle factor | 5th obstacle factor | |
| 2011 | X16 (13.69) | X2 (8.98) | X15 (7.53) | X14 (7.49) | X9 (7.00) |
| 2012 | X16 (13.92) | X2 (9.08) | X14 (7.50) | X15 (7.44) | X9 (7.03) |
| 2013 | X16 (14.13) | X2 (9.15) | X14 (7.50) | X15 (7.36) | X9 (7.02) |
| 2014 | X16 (14.36) | X2 (9.24) | X14 (7.57) | X15 (7.39) | X7 (6.97) |
| 2015 | X16 (14.64) | X2 (9.41) | X14 (7.56) | X15 (7.51) | X7 (7.04) |
| 2016 | X16 (14.88) | X2 (9.51) | X14 (7.64) | X15 (7.56) | X7 (7.05) |
| 2017 | X16 (14.94) | X2 (9.53) | X14 (7.62) | X15 (7.59) | X7 (7.00) |
| 2018 | X16 (15.04) | X2 (9.64) | X15 (7.70) | X5 (7.65) | X14 (7.49) |
| 2019 | X16 (15.25) | X2 (9.85) | X5 (7.99) | X14 (7.95) | X15 (7.62) |
| 2020 | X16 (15.51) | X2 (10.22) | X5 (8.34) | X14 (7.86) | X15 (7.29) |
| 2021 | X16 (15.84) | X2 (10.83) | X5 (8.66) | X14 (7.85) | X15 (7.35) |
