Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.05688 -0.03395 -0.01413  0.02025  0.26849 

Coefficients:
                      Estimate Std. Error t value             Pr(>|t|)    
(Intercept)           0.042249   0.002591  16.306 < 0.0000000000000002 ***
xLow income          -0.021846   0.005832  -3.746             0.000194 ***
xLower middle income -0.013736   0.004690  -2.929             0.003510 ** 
xNA                   0.014634   0.008935   1.638             0.101926    
xUpper middle income -0.008210   0.004331  -1.896             0.058407 .  
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.04525 on 707 degrees of freedom
Multiple R-squared:  0.03373,	Adjusted R-squared:  0.02826 
F-statistic:  6.17 on 4 and 707 DF,  p-value: 0.00006981