Call:
lm(formula = y ~ x)

Residuals:
      Min        1Q    Median        3Q       Max 
-0.032983 -0.018992 -0.010799  0.009944  0.297629 

Coefficients:
                      Estimate Std. Error t value             Pr(>|t|)    
(Intercept)           0.032984   0.001974  16.712 < 0.0000000000000002 ***
xLow income          -0.018517   0.004443  -4.168            0.0000346 ***
xLower middle income -0.015482   0.003572  -4.334            0.0000168 ***
xNA                  -0.008184   0.006807  -1.202                 0.23    
xUpper middle income -0.013978   0.003299  -4.237            0.0000257 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.03447 on 707 degrees of freedom
Multiple R-squared:  0.04675,	Adjusted R-squared:  0.04135 
F-statistic: 8.668 on 4 and 707 DF,  p-value: 0.0000007828