Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.02472 -0.02469 -0.00432 -0.00286  0.94672 

Coefficients:
                      Estimate Std. Error t value    Pr(>|t|)    
(Intercept)           0.024723   0.004660   5.305 0.000000151 ***
xLow income          -0.024129   0.010490  -2.300     0.02172 *  
xLower middle income -0.021439   0.008435  -2.542     0.01124 *  
xNA                  -0.024453   0.016071  -1.522     0.12856    
xUpper middle income -0.020396   0.007790  -2.618     0.00903 ** 
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.08139 on 707 degrees of freedom
Multiple R-squared:  0.01744,	Adjusted R-squared:  0.01188 
F-statistic: 3.136 on 4 and 707 DF,  p-value: 0.01428