Fig. 2
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs13018-021-02592-2/MediaObjects/13018_2021_2592_Fig2_HTML.png)
Ethnic group comparison. Data presented as mean standard deviation. *Statistical significance for p < 0.05 (t-test). x < 40, people younger than 40 years old; 40 < x < 60, people between 40 and 60 years old; x > 60, people older than 60 years old; x < 50, people younger than 50 years old; x > 50, people older than 50 years old