A patient population was divided into 3 categories:

Young patients (n=19) / Middle aged patients (n=66) / Old patients (n =20)

Based on a questionairre, we have categorized each patient into 2 categories: "Yes family history of diabetes" or "no family history of diabetes".

The data was as follows:

Young patients (n=19):

Yes Family Hx = 7

No Family Hx = 12

So, % of patients with "Yes Family Hx" = 37%

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Middle aged patients (n=66):

Yes Family Hx = 21

No Family Hx = 45

So, % of patients with "Yes Family Hx" = 32%

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Old patients (n =20):

Yes Family Hx = 1

No Family Hx = 19

So, % of patients with "Yes Family Hx" = 5%

I have used Chi square table to test whether the differences between the 3 groups is statistically significant.

**My question is:

Is there any way I compare these 3 groups using the PRECENTAGE data above? I am asking because I want to represent this data in a graph as follows:

Y axis = % of patients

X axis = Each of the 3 categories of ages as bar graphs.

Most importantly, I want to indicate on this graph whether the % in each age group DIFFER FROM EACH OTHER STATISTICALLY.

A graph similar to what I want to do is found in Figure 1 of this paper: http://circ.ahajournals.org/cgi/content/abstract/74/4/712