Como dizer "atendimentos/mês" em inglês

I think depends on what you are translating. For instance, they often use mpg (not m/g), on the other hand they may use Km/L.

http://www.convertworld.com/en/fuel-con ... allon.html




Even so, on the Internet rarely one sees the use of slashes to indicate ratio would sound ''bookish" to me. More acceptable though, in more formal matters, like accountancy perhaps. Or in classrooms when writing (and explaining) formulas etc.
In the sites, spreadsheets, or reports I saw (including ones of OECD, NHS etc.) they don´t use slashes, to represent that they say something like "...per year/by year etc.)


Examples:
1)
The 35,926 discharges in 2012/13 involved 24,266 patients; an average number of 1.48 alcohol-related discharges per patient.

2)
The 35,926 discharges in 2012/13 involved 24,266 patients; an average number of 1.48 alcohol-related discharges per patient





https://www.zionsbank.com/pdfs/biz_resources_book-6.pdf
A ratio, you will remember from school, is the relationship between two numbers. As your math teacher might have put it, it is “the relative size of two quantities, expressed as the quotient of one divided by the other.” If you are thinking about buying shares of a publicly-traded company, you might look at its price-earnings ratio. If the stock is selling for $60 per share, and the company’s earnings are $2 per share, the ratio of price ($60) to earnings ($2) is 30 to 1. In common usage, we would say the “P/E ratio is 30.”
Financial ratio analysis can be used in two different but equally useful ways. You can use them to examine the current performance of your company in comparison to past periods of time, from the prior quarter to years ago. Frequently, this can help you identify problems that need fixing. Even better, it can direct your attention to potential problems that can be avoided. In addition, you can use these ratios to compare the performance of your company against that of your competitors or other members of your industry.
Remember the ratios you will be calculating are intended simply to show broad trends and thus to help you with your decision-making. They need only to be accurate enough to be useful to you. Don’t get bogged down calculating ratios to more than one or two decimal places. Any change measured in hundredths of a percent will almost certainly have no meaning. Make sure your math is correct, but don’t agonize over it.
A ratio can be expressed in several ways. A ratio of two-to-one can be shown as:
2:1 2-to-1 2/1
In these pages, when we present a ratio in the text it will be written out, using the word “to.” If the ratio is in a formula, the slash sign (/) will be used to indicate division.

I have seen it used to indicate price/cost as well, but then, not related to statistics.

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http://www.consumerreports.org/cro/abou ... /index.htm

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Means "por mês" but nothing statistical here.

Services/month = services per month


cheers !