no it wouldn't the percentage would be the same.
For simplicity's sake we say 2% of a population of 100 million work in railway related activities, ie 2 million. A population of 100 million translates to 25 million POPs, who are assumed to represent your entire work force. Of that 25 million, 2 million = 8% are working in rail.
Of course this is based on the assumption the game makes that exactly 25% of each segment of your population is your available workforce, while the other 75% are not interested in employment.
That's the important part. The rest is if you need more convincing (though I'm too tired to guarantee it will make sense):
There are situations where the percentage is unchanged by the POP = 4 people set up, for example implementing women's suffrage. Some people make the mistake that it would benefit the more populace lower class, but the proportions in that case are unchanged. If your POP make up is 6 poor:3 middle:1 rich (60%:30%:10%), and you double each class' vote by going from male universal suffrage to giving females the vote too, the split will still be 60%:30%:10% (though the absolute differences will be larger, this would only make a difference if Mrs Smith were allowed to vote differently to Mr Smith - complexity that is not needed yet).
To work out whether the percentages will change, you need to know whether the population you're considering has changed, and whether the subset sizes have changed. For the women's suffrage case, voting population has doubled, but so has each class-subset's population, therefore no change in percentage terms. For our railway workers case, the population under consideration has changed from your whole country's 100 million to just the workforce of 25 million (by ignoring the 75 million not seeking employment), but the railway workers subset is unchanged at 2 million (because they're entirely made up of members of the workforce, you haven't cut any of them). Therefore there is a change in percentage, ie what I showed in the first paragraph.
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As for the gold, it sounds good to me.