Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.05922 -0.02496 -0.00047  0.01261  0.11327 

Coefficients:
                       Estimate Std. Error t value           Pr(>|t|)    
(Intercept)           0.0422257  0.0049788   8.481 0.0000000000000244 ***
xLow income           0.0072606  0.0089305   0.813             0.4176    
xLower middle income  0.0170078  0.0077398   2.197             0.0296 *  
xNA                  -0.0004701  0.0359025  -0.013             0.9896    
xUpper middle income  0.0012824  0.0076195   0.168             0.8666    
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.03556 on 144 degrees of freedom
Multiple R-squared:  0.0375,	Adjusted R-squared:  0.01076 
F-statistic: 1.403 on 4 and 144 DF,  p-value: 0.2361