Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.08724 -0.03751 -0.01777  0.00000  0.46326 

Coefficients:
                      Estimate Std. Error t value Pr(>|t|)   
(Intercept)           0.024083   0.013024   1.849  0.06648 . 
xLow income          -0.007286   0.023361  -0.312  0.75559   
xLower middle income  0.013442   0.020246   0.664  0.50781   
xNA                  -0.017773   0.093915  -0.189  0.85017   
xUpper middle income  0.063163   0.019931   3.169  0.00187 **
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.09301 on 144 degrees of freedom
Multiple R-squared:  0.08166,	Adjusted R-squared:  0.05615 
F-statistic: 3.201 on 4 and 144 DF,  p-value: 0.01492