I think you want the ecdf function rather than quantile.
mydata <- data.frame("hp"=mtcars$hp)
library(dplyr)
#>
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#>
#> filter, lag
#> The following objects are masked from 'package:base':
#>
#> intersect, setdiff, setequal, union
ECDF <- ecdf(mydata$hp)
mydata <- mydata %>% mutate(Perc = ECDF(hp))
head(mydata)
#> hp Perc
#> 1 110 0.43750
#> 2 110 0.43750
#> 3 93 0.21875
#> 4 110 0.43750
#> 5 175 0.68750
#> 6 105 0.31250
Created on 2021-05-04 by the reprex package (v0.3.0)