Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.19661 -0.01887 -0.00805  0.00528  0.40457 

Coefficients:
                      Estimate Std. Error t value             Pr(>|t|)    
(Intercept)           0.064396   0.003600  17.887 < 0.0000000000000002 ***
xLow income          -0.063784   0.008104  -7.871   0.0000000000000132 ***
xLower middle income -0.056336   0.006516  -8.646 < 0.0000000000000002 ***
xNA                   0.132213   0.012415  10.649 < 0.0000000000000002 ***
xUpper middle income -0.045527   0.006018  -7.565   0.0000000000001207 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.06287 on 707 degrees of freedom
Multiple R-squared:  0.2997,	Adjusted R-squared:  0.2957 
F-statistic: 75.63 on 4 and 707 DF,  p-value: < 0.00000000000000022