Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.06377 -0.02257 -0.01873  0.01393  0.25655 

Coefficients:
                      Estimate Std. Error t value Pr(>|t|)    
(Intercept)           0.021318   0.006232   3.421 0.000813 ***
xLow income           0.042463   0.011179   3.799 0.000214 ***
xLower middle income  0.026828   0.009688   2.769 0.006361 ** 
xNA                  -0.021301   0.044940  -0.474 0.636224    
xUpper middle income  0.010607   0.009538   1.112 0.267927    
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.04451 on 144 degrees of freedom
Multiple R-squared:  0.1117,	Adjusted R-squared:  0.08699 
F-statistic: 4.525 on 4 and 144 DF,  p-value: 0.001793