Fig. 7

Percentile curve for scores for professional oral hygiene care. This graph presents the rate of increasing skill scores of nurses according to the number of practices. The black line indicated the median of scores, the red line indicated the percentile between 3 and 97%, and the green line indicated the percentile from 15 to 85%. The percentile from 3–15 is assumed the weak level, 15–50% is assumed the middle level, 50–85% is assumed a good level, and 85–90% is assumed a well level